Van top extension



FIG. 1 is a perspective view of a van top extension embodying my new design;

FIG. 2 is a rear end elevational view thereof, opposite to the front end shown in FIG. 1;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a top plan view thereof, and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a van top extension, as shown. 